Annular Isolators for Expandable Tubulars in Wellbores

ABSTRACT

The present disclosure addressed apparatus and methods for forming an annular isolator in a borehole after installation of production tubing. Annular seal means are carried in or on production tubing as it is run into a borehole. In conjunction with expansion of the tubing, the seal is deployed to form an annular isolator. An inflatable element carried on the tubing may be inflated with a fluid carried in the tubing and forced into the inflatable element during expansion of the tubing. Reactive chemicals may be carried in the tubing and injected into the annulus to react with each other and ambient fluids to increase in volume and harden into an annular seal. An elastomeric sleeve, ring or band carried on the tubing may be expanded into contact with a borehole wall and may have its radial dimension increased in conjunction with tubing expansion to form an annular isolator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Divisional Application of U.S. patent application Ser. No.11/833,309, filed Aug. 3, 2007, entitled “Annular Isolators forExpandable Tubulars in Wellbores” which is a Divisional Application ofU.S. patent application Ser. No. 10/981,822, filed Nov. 5, 2004, nowU.S. Pat. No. 7,252,142, issued Aug. 7, 2007, entitled “AnnularIsolators for Expandable Tubulars in Wellbores” which is a divisional ofU.S. Pat. No. 6,854,522, issued Feb. 15, 2005, entitled “AnnularIsolators For Expandable Tubulars In Wellbores” and claims priority toand hereby incorporates all by reference for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to isolating the annulus between tubular membersin a borehole and the borehole wall, and more particularly to methodsand apparatus for forming annular isolators in place in the annulusbetween a tubular member and a borehole wall.

It is well known that oil and gas wells pass through a number of zonesother than the particular oil and/or gas zones of interest. Some ofthese zones may be water producing. It is desirable to prevent waterfrom such zones from being produced with produced oil or gas. Wheremultiple oil and/or gas zones are penetrated by the same borehole, it isdesirable to isolate the zones to allow separate control of productionfrom each zone for most efficient production. External packers have beenused to provide annular seals or barriers between production tubing andwell casing to isolate various zones.

It has become more common to use open hole completions in oil and gaswells. In these wells, standard casing is cemented only into upperportions of the well, but not through the producing zones. Tubing isthen run from the bottom of the cased portion of the well down throughthe various production zones. As noted above, some of these zones maybe, for example, water zones which must be isolated from any producedhydrocarbons. The various production zones often have different naturalpressures and must be isolated from each other to prevent flow betweenzones and to allow production from the low pressure zones.

Open hole completions are particularly useful in slant hole wells. Inthese wells, the wellbore may be deviated and run horizontally forthousands of feet through a producing zone. It is often desirable toprovide annular isolators along the length of the horizontal productiontubing to allow selective production from, or isolation of, variousportions of the producing zone.

In open hole completions, various steps are usually taken to preventcollapse of the borehole wall or flow of sand from the formation intothe production tubing. Use of gravel packing and sand screens are commonways of protecting against collapse and sand flow. More moderntechniques include the use of expandable solid or perforated tubingand/or expandable sand screens. These types of tubular elements may berun into uncased boreholes and expanded after they are in position.Expansion may be by use of an inflatable bladder or by pulling orpushing an expansion cone through the tubular members. It is desirablefor expanded tubing and screens to minimize the annulus between thetubular elements and the borehole wall or to actually contact theborehole wall to provide mechanical support and restrict or preventannular flow of fluids outside the production tubing. However, in manycases, due to irregularities in the borehole wall or simplyunconsolidated formations, expanded tubing and screens will not preventannular flow in the borehole. For this reason, annular isolators asdiscussed above are typically needed to stop annular flow.

Use of conventional external casing packers for such open holecompletions presents a number of problems. They are significantly lessreliable than internal casing packers, they may require an additionaltrip to set a plug for cement diversion into the packer, and they arenot compatible with expandable completion screens.

Efforts have been made to form annular isolators in open holecompletions by placing a rubber sleeve on expandable tubing and screensand then expanding the tubing to press the rubber sleeve into contactwith the borehole wall. These efforts have had limited success dueprimarily to the variable and unknown actual borehole shape anddiameter. The thickness of the sleeve must be limited since it adds tothe overall tubing diameter, which must be limited to allow the tubingto be run into the borehole. The maximum size must also be limited toallow tubing to be expanded in a nominal or even undersized borehole. Inwashed out or oversized boreholes, normal tubing expansion is not likelyto expand the rubber sleeve enough to contact the borehole wall and forma seal. To form an annular seal or isolator in variable sized boreholes,adjustable or variable expansion tools have been used with some success.However it is difficult to achieve significant stress in the rubber withsuch variable tools and this type of expansion produces an inner surfaceof the tubing which follows the shape of the borehole and is not ofsubstantially constant diameter.

It would be desirable to provide equipment and methods for installingannular isolators in open boreholes, particularly horizontal boreholes,which may be carried on tubular elements as installed in a borehole andprovide a good seal between production tubing and the wall of openboreholes.

SUMMARY OF THE INVENTION

The present invention provides apparatus which may be carried on or intubing as it is run into a wellbore and deployed to form an annularisolator between the tubing and borehole. In a preferred form, thetubing is expandable tubing and the annular isolator is activated ordeployed as a result of or in conjunction with expansion of the tubing.In one embodiment, an annular isolator forming material is in acompartment carried with the tubing as it is installed in a borehole andis driven from the compartment to form an annular isolator inconjunction with tubing expansion. The annular isolator forming materialmay be placed into the annulus between the tubing and borehole wallwhere it acts as an annular isolator due to its inherent viscosity or asa result of a chemical reaction which converts the material into aviscous, semisolid or solid material in place in the annulus. Thematerial may include several chemical components which react with eachother, or may be a single or multiple chemical components, which alsoreact with ambient fluids to form an annular isolator.

In another form, the present invention includes an inflatable membercarried on the outside of a tubing section. Any of the above describedannular isolator forming materials may be flowed into the inflatablemember to inflate it and form an annular isolator. In one form of theinvention, the inflatable member includes multiple sections, whichinflate at progressively increasing pressure levels. A section whichinflates at the lowest pressure level is designed to expand to fill thelargest expected annulus, while the other sections inflate only afterthe low pressure section contacts a borehole wall. The inflatable membermay be inflated with material carried with the tubing in a compartmentand driven from the compartment into the inflatable member as a resultof tubing expansion. It may also be inflated with material pumped downthe tubing itself or through a work string positioned in the tubing.

In another form of the invention, the annular isolator forming materialis an elastomeric sleeve, band or ring carried on expandable tubing asit is installed in a borehole and deployed to act as an annular isolatorin conjunction with expansion of the tubing. In one form, one, orpreferably multiple, rings have radial and axial dimensions and shapesselected to form a fluid tight seal with a maximum borehole size aftertubing expansion, and to form a seal after tubing expansion in a minimumsized borehole without exceeding maximum allowable stress. In otherforms, a sleeve has a reduced radial dimension as installed on tubingfor running into a borehole where its radial dimension is increasedprior to or in conjunction with tubing expansion. In one form the sleeveis stretched axially as installed on the tubing and held in place by aslidable ring during tubing installation. Upon tubing expansion the ringis released and the sleeve is allowed to return to its original radialdimension. In another form the slidable ring is driven by an expansioncone to axially compress an elastomeric sleeve and increase its radialdimension. Both mechanisms may be applied to the same elastomericsleeve. In another form, the sleeve is designed to fold upon itself orinto a circumferentially corrugated shape upon axial compression, toincrease its radial dimension. Pairs of such elastomeric sleeves, bandsor rings may be used to isolate a section of annulus into which annularisolator forming material carried with the tubing or conveyed down holethrough tubing or a work string may be placed as discussed above.

Although the embodiments of the present invention are intended toproduce annular isolators in conjunction with tubing expansion with afixed expansion cone type tool, other expansion means may also be usedto advantage. Inflatable bladders may be used for primary expansion, orfor overexpanding tubing sections which carry annular isolator formingmaterials including elastomeric sleeves, rings or bands. Adjustable orvariable diameter expansion cone tools may be used to overexpand tubingsections which carry annular isolator forming materials includingelastomeric sleeves, rings or bands. Internal pressure applied throughthe tubing or a work string may be used to overexpand selected tubingsections. Axial compression of the selected tubing sections may be usedto aid over expansion of such selected tubing sections. Finally, one ofskill in the art will also recognize that some of the describedembodiments will function and provide many of the same advantages evenwhen used in combination with tubing which is not expanded and/or in aportion of the borehole which has been cased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a borehole in the earth with an openhole completion and a number of annular isolators according to thepresent invention.

FIG. 2 is a cross-sectional illustration of expandable tubing in an openhole completion carrying elastomeric rings or bands on the outer surfaceof the tubing.

FIG. 3 is a cross-sectional illustration of an elastomeric sleeve on theouter surface of expandable tubing, which has been prestretched toreduce its thickness during installation of the tubing in the borehole.

FIG. 4 is a cross-sectional illustration of the embodiment of FIG. 3after the prestretched sleeve has been released by an expansion cone.

FIG. 5 is an illustration of use of an adjustable expansion cone toexpand expandable tubing and an elastomeric sleeve into an enlargedportion of an open borehole to form an annular isolator.

FIGS. 6 and 7 are cross-sectional illustrations of an embodimentincluding elastomeric sleeves on the outer surface of an expandabletubing which are folded before tubing expansion to form an annularisolator in an enlarged portion of a borehole.

FIGS. 8 and 9 are cross-sectional illustrations of latching mechanismsfor holding the elastomeric sleeve of FIGS. 6 and 7 in place duringinstallation of tubing in a borehole.

FIG. 10 is a cross-sectional illustration of expandable tubing carryingreactive chemicals in a matrix on its outer surface for installation ina borehole.

FIG. 11 is a cross-sectional illustration of expandable tubing carryingreactive chemicals in a reduced diameter portion for installation in aborehole.

FIG. 12 is a cross-sectional illustration of expandable tubing carryinga fluid within a reduced diameter portion and covered by an expandablesleeve having a pressure relief valve.

FIG. 13 is a cross-sectional illustration of expandable tubing having areduced diameter corrugated section carrying a fluid and covered by anexpandable sleeve having a pressure release valve.

FIG. 14 is a cross-sectional view of the FIG. 13 embodiment whichillustrates corrugated expandable tubing and the location of annularisolator forming material.

FIG. 15 is a partial cross-sectional illustration of another embodimentof the present invention having an annular isolator forming fluidcarried within a recess in expandable tubing and arranged to inflate anelastomeric sleeve upon tubing expansion.

FIG. 16 illustrates the condition of the FIG. 14 embodiment after theexpandable tubing has been expanded.

FIGS. 17, 18, and 19 are cross-sectional illustrations of an expandabletubing assembly having an elastomeric sleeve which can be expanded aspart of the tubing expansion process.

FIG. 20 is a cross sectional illustration of an alternative form of theembodiment of FIGS. 17, 18 and 19.

FIGS. 21, 22, and 23 are cross-sectional illustrations of an elastomericsleeve with an embedded spring that may be carried on an expandabletubing and released to form an annular isolator as a result of expansionof the tubing.

FIGS. 24 and 25 are illustrations of expandable tubing having aninflatable bladder and a two part chemical system driven by aspring-loaded piston for inflating the bladder as part of expansion ofthe tubing.

FIG. 26 is a partially cross-sectional view of an expandable tubularelement carrying a compressed foam sleeve held in position by a gridwhich may be released upon expansion of the tubing.

FIG. 27 is a cross-sectional illustration of expandable tubing carryinga sleeve which may be expanded by a chemical reaction driving a pistonwhich is initiated by expansion of the tubing.

FIGS. 28 and 29 are illustrations of expandable tubing carrying foldedplates which may be expanded to form a basket upon expansion of thetubing.

FIG. 30 is a cross-sectional illustration of expandable tubing having aninterior chamber carrying an annular isolator forming material which maybe forced into an external inflatable sleeve upon passage of anexpansion cone through the expandable tubing.

FIG. 31 is a cross-sectional illustration of expandable tubing carryingan inflatable rubber bladder on a recessed portion and an expansionstring to fill the rubber bladder with fluid pumped from the surfaceprior to running of an expansion cone through the reduced diameterportion of the tubing.

FIG. 32 is a cross-sectional illustration of expandable tubing carryingan elastomeric sleeve and an expansion tool used to expand the tubinginto contact with the borehole using pressure fluid pumped from thesurface.

FIGS. 33 and 34 are cross-sectional illustrations of system using anaxial load and interior pressure to cause expansion of expandable tubingand an external sleeve into contact with a borehole wall to form anannular isolator.

FIG. 35 is a cross-sectional illustration of expanded tubing and aninjection tool for placing an annular isolator forming material in theannulus between the expanded tubing and the borehole wall.

FIG. 36, is a cross sectional illustration of an alternate system forpreexpanding an externally carried elastomeric sleeve of the type shownin FIGS. 6 to 9.

FIG. 37 is a cross sectional illustration of yet another system forpreexpanding an externally carried elastomeric sleeve of the type shownin FIGS. 6 to 9.

FIGS. 38, 39, 40 and 41 illustrate the deployment of an external sleevehaving multiple sections which inflate at different internal pressurelevels to form an annular isolator.

FIG. 42 is a cross sectional illustration of an embodiment having aconduit in the annulus passing through an inflatable isolator.

FIG. 43 is a more detailed illustration of a portion of FIG. 42.

FIG. 44 is an illustration of a pair of conduits located in an annulusand bypassing an inflatable isolator element.

FIG. 45 is an illustration of a circumferentially corrugated elastomericsleeve which may be used to form an annular isolator.

DETAILED DESCRIPTION OF THE INVENTION

The term “annular isolatoc” as used herein means a material or mechanismor a combination of materials and mechanisms which blocks or preventsflow of fluids from one side of the isolator to the other in the annulusbetween a tubular member in a well and a borehole wall or casing. Anannular isolator acts as a pressure bearing seal between two portions ofthe annulus. Since annular isolators must block flow in an annularspace, they may have a ring like or tubular shape having an innerdiameter in fluid tight contact with the outer surface of a tubularmember and having an outer diameter in fluid tight contact with theinner wall of a borehole or casing. An annular isolator could be formedby tubing itself if it could be expanded into intimate contact with aborehole wall to eliminate the annulus. An isolator may extend for asubstantial length along a borehole. In some cases, as described below,a conduit may be provided in the annulus passing through or bypassing anannular isolator to allow controlled flow of certain materials, e.g.hydraulic fluid, up or down hole.

The term “perforated” as used herein, e.g. perforated tubing orperforated liner, means that the member has holes or openings throughit. The holes can have any shape, e.g. round, rectangular, slotted, etc.The term is not intended to limit the manner in which the holes aremade, i.e. it does not require that they be made by perforating, or thearrangement of the holes.

With reference now to FIG. 1, there is provided an example of aproducing oil well in which an annular isolator according to the presentinvention is useful. In FIG. 1, a borehole 10 has been drilled from thesurface of the earth 12. An upper portion of the borehole 10 has beenlined with casing 14 which has been sealed to the borehole 10 by cement16. Below the cased portion of borehole 10 is an open hole portion 18which extends downward and then laterally through various earthformations. For example, the borehole 18 may pass through a waterbearing zone 20, a shale layer 21, an oil bearing zone 22, anonproductive zone 23 and into another oil bearing zone 24. Asillustrated in FIG. 1, the open hole 18 has been slanted so that it runsthrough the zones 20-24 at various angles and may run essentiallyhorizontally through oil-bearing zone 24. Slant hole or horizontaldrilling technology allows such wells to be drilled for thousands offeet away horizontally from the surface location of a well and allows awell to be guided to stay within a single zone if desired. Wellsfollowing an oil bearing zone will seldom be exactly horizontal, sinceoil bearing zones are normally not horizontal.

Tubing 26 has been placed to run from the lower end of casing 14 downthrough the open hole portion of the well 18. At its upper end, thetubing 26 is sealed to the casing 14 by an annular isolator 28. Anotherannular isolator 29 seals the annulus between tubing 26 and the wall ofborehole 18 within the shale zone 21. It can be seen that isolators 28and 29 prevent annular flow of fluid from the water zone 20 and therebyprevent production of water from zone 20. Within oil zone 22, tubing 26has a perforated section 30. Section 30 may be a perforated liner andmay typically carry sand screens or filters about its outercircumference. A pair of annular isolators 31 prevents annular flow to,from or through the nonproductive zone 23. The isolators 31 may be asingle isolator extending completely through the zone 23 if desired. Thecombination of isolator 29 and isolators 31 allow production from oilzone 22 into the perforated tubing section 30 to be selectivelycontrolled and prevents the produced fluids from flowing through theannulus to other parts of the borehole 18. Within oil zone 24, tubing 26is illustrated as having two perforated sections 32 and 33. Sections 32and 33 may be perforated and may typically carry sand screens or filtersabout their outer circumference. Annular isolators 36 and 38 areprovided to seal the annulus between the tubing 26 and the wall of openborehole 18. The isolators 31, 36 and 38 allow separate control of flowof oil into the perforated sections 32 and 33 and prevent annular flowof produced fluids to other portions of borehole 18. The horizontalsection of open hole 18 may continue for thousands of feet through theoil bearing zone 24. The tubing 26 may likewise extend for thousands offeet within zone 24 and may include numerous perforated sections whichmay be divided by numerous annular isolators, such as isolators 36 and38, to divide the zone 24 into multiple areas for controlled production.

It is becoming more common for the tubing 26 to comprise expandabletubular sections. Both the solid sections of the tubing 26 and theperforated sections 32 and 33 are now often expandable. The use ofexpandable tubing provides numerous advantages. The tubing is of reduceddiameter during installation which facilitates installation in offset,slanted or horizontal boreholes. Upon expansion, solid, or perforatedtubing and screens provide support for uncased borehole walls whilescreening and filtering out sand and other produced solid materialswhich can damage tubing. After expansion, the internal diameter of thetubing is increased improving the flow of fluids through the tubing.Since there are limits to which expandable tubing 26 may be expanded andthe borehole walls are irregular and may actually change shape duringproduction, annular flow cannot be prevented merely by use of expandabletubing 26, including expandable perforated sections and screens 32 and33. To achieve the desirable flow control, annular barriers or isolators36 and 38 are needed. Typical annular isolators such as inflatablepackers have not been found compatible with the type of productioninstallation illustrated in FIG. 1 for various reasons including thefact that the structural members required to mount and operate suchpackers are not expandable along with the tubing string 26.

With reference to FIG. 2, an improved system and method of installationof annular isolators such as elements 36 and 38 shown in FIG. 1 isprovided. In FIG. 2 is illustrated an expandable tubing 42 positionedwithin an open borehole 40. On the right side of FIG. 2, the tubing isshown in its unexpanded state and carries on it outer surface a ring orband of elastomeric material 44, for example rubber. In this embodiment,the ring 44 has fairly short axial dimensions, i.e. its length along theaxial length of the tubing 42, but has a relatively long radialdimension, i.e. the distance it extends from the tubing in the radialdirection towards the borehole wall 40. The rings are preferably taperedradially as illustrated to have a longer axial dimension where bonded tothe outer surface of the tubing and shorter axial dimension on the endwhich first contacts the borehole wall. As run into the borehole, thetubing 42 carries ring 44 and a similar ring 46 which together may forma single annular isolator such as isolator 36 in FIG. 1. The rings 44and 46 may be installed on the tubing 42 by being cast in a moldpositioned around the tubing 42. The tubing may also be covered by acontinuous sleeve of elastomer between rings 44 and 46 which may beformed in the same casting and curing process. Also shown in FIG. 2 isan expansion cone 48 which has been driven into the expandable tubing 42from the left side as indicated by arrow 50. As the cone passes throughthe tubing from left to right, the tubing is expanded to a largerdiameter as indicated at 52. As the expansion cone passed through thering 46, the ring 46 was forced into contact with the wall 40. Expansionof the tubing 52 reduced the radial dimension and increased the axialdimension of the ring 46, since the total volume must remain constant.Stated otherwise, the ring 46 was partially displaced axially in theannulus between the expanded tubing 52 and borehole 40. When theexpansion cone 48 passes through ring 44, it will likewise be expandedinto contact with the borehole wall 40. Each annular isolator 36, 38 ofFIG. 1 may comprise two or more such rubber rings 44 and 46 carried onexpandable tubing as illustrated in FIG. 2.

Also illustrated in FIG. 2 is a conduit 45 extending along the outersurface of tubing 42 and passing through the rings 44 and 46. It isoften desirable in well completions to provide control, signal, power,etc. lines from the surface to down hole equipment. The lines may becopper or other conductive wires for conducting electrical power downhole or for sending control signals down hole and signals from pressure,temperature, etc. sensors up hole. Fiber optic lines may also be usedfor signal transmissions up or down hole. The lines may be hydrauliclines for providing hydraulic power to down hole valves, motors, etc.Hydraulic lines may also be used to provide control signals to down holeequipment. The conduit 45 may be any other type of line, e.g. a chemicalinjection line, used in a down hole environment. It is usually preferredto route these lines on the outside of the tubing rather than in theproduction flow path up the center of the tubing. The lines can berouted through the rubber rings 44 and 46 as illustrated whilemaintaining isolation of the annulus with the rings 44, 46.

The FIG. 2 embodiment solves several problems of prior art devices. Suchdevices have included relatively thin rubber sleeves on the outside ofexpandable screens, which sleeves extend for substantial distancesaxially along the tubing. In enlarged portions of open boreholes suchsleeves typically do not make contact with the borehole and thus do notform an effective annular isolator. In well consolidated formations,such prior art sleeves may contact the borehole wall before theexpandable tubing is fully expanded creating excessive forces in theexpansion process. Due to their axial length, the forces required toextrude or flow such sleeves axially in the annulus cannot be generatedby an expansion tool and, if they could, would damage the borehole orthe tubing.

In the FIG. 2 embodiment, the elastomeric rings 44 and 46 have radialand axial dimensions selected to achieve several requirements. Onerequirement is for the rings to contact a borehole wall with sufficientstress to conform to the borehole wall and act as an effective annularisolator. The radial dimension or height of the ring therefore isselected to be greater than the width of the annulus between expandedtubing and the wall of the largest expected borehole. The ring willtherefore be compressed radially and will expand axially in the annulusas a result of tubing expansion. By proper selection of elastomericmaterial and the axial length of the ring relative to the radialdimension, a minimum stress level can be generated to provide a sealwith the borehole wall.

Another requirement is to avoid damage which may result from excessivestress in the rings 44, 46. Excessive stresses may be encountered whentubing is expanded in a borehole having a nominal or less than nominaldiameter. Such excessive stress may damage the borehole wall, i.e. theformation, by overstressing and crushing the borehole wall. In somecases, some compression of the borehole wall is acceptable or evendesirable. Excessive stress can also cause collapse or compression ofthe tubing after an expansion tool has passed through the rings. Thatis, the stress in the elastomeric rings may be sufficient to reduce thetubing diameter after an expansion tool has passed through the tubing orbeen removed. Excessive stress may damage or stop movement of anexpansion tool itself. That is, the stress may require forces greaterthan those available from a given expansion tool.

When expanding tubing in minimum diameter boreholes, the elastomericrings must be capable of axial expansion at internal stresses which arebelow levels which would cause damage to the borehole wall, tubing orexpansion tool. The radial dimension of the rings is selected asdiscussed above. Based on any given radial dimension and thecharacteristics of the selected elastomer, the axial dimension of thering is selected to allow expansion of the tubing in the smallestexpected borehole without generating excessive pressures. The smallerthe axial dimension, the less force is required to compress theelastomeric ring radially from its original radial dimension to thethickness of the annulus between the expanded tubing and the smallestexpected borehole.

The tapered shape of the rings 44, 46 is one way in which therequirements can be achieved. As is apparent from the above discussion,the amount of force required to radially compress the rings 44, 46 isrelated to the axial length of the rings. With a tapered shape as shownin FIG. 2 (or the tapers shown in FIGS. 10 and 11), the ring does nothave a single axial dimension, but instead has a range of axialdimensions. The shortest axial dimension is on the outer circumferencewhich will first contact a borehole wall. The force required to causeradial compression and axial expansion is therefore smallest at theouter circumference. That is, the deformation of the ring during tubingexpansion effectively begins with the portion which first contacts theborehole wall. This helps insure conformance of the ring with theborehole wall surface. The same effect can be achieved with other crosssectional shapes of the rings 44, 46 such as hemispherical or parabolicwhich would also provide a greater axial dimension adjacent the tubingand shorter axial dimension at the outer circumference of the rings.

It is preferred that an annular isolator according to the FIG. 2embodiment include two or more of the illustrated rings 44, 46. It isalso preferred that the axial dimensions of the rings be selected toallow annular expansion or extrusion of the elastomer as the ring iscompressed radially. This assumes, of course, that there is availableannular space into which the elastomer may expand without restriction.If adjacent rings are spaced too closely, they could contact each otheras they expand axially in the annulus. Upon making such contact, theforces required for further radial compression may increasesubstantially. It is therefore preferred that adjacent rings 44, 46 bespaced apart sufficiently to allow unrestricted annular expansion atleast in the minimum sized borehole. Since elastomers such as rubber areessentially incompressible, sufficient annular volume should beavailable to accommodate the volume of elastomeric material which willbe displaced axially by the greatest radial compression of the rings.While the illustrated embodiment shows an absence of material betweenthe two rings, as discussed above, there may also be a radially shorterlinking sleeve section between the two rings. Even in such a case, thedesign could still be implemented to provide available volume (space)above the sleeve section between the two rings to accommodate thedesired expansion.

With reference the FIGS. 3 and 4, another embodiment of an externalannular isolator is illustrated. In FIG. 3 is shown a portion of anunexpanded expandable tubular member 54. Carried on the outside ofexpandable member 54 is a pre-stretched elastomeric sleeve 56. Sleeve 56has been stretched axially to increase its axial dimension and reduceits radial dimension from the dimensions it has when free of suchexternal forces. One end of sleeve 56 is attached to a ring 58 which maybe permanently attached to the outer surface of tubular member 54 bywelding or may be releasably attached by bonding or crimping asdiscussed below. On the other end of elastomeric sleeve 56 is attached asliding ring 60 which is captured in a recess 62 in the tubing 54. InFIG. 4, the elastomeric sleeve 56 is illustrated in its relaxed orunstretched condition free of the stretching force. In FIG. 4, theexpansion cone 64 has been forced into the expandable member 54 from theleft side and has moved past the locking recess 62. As it did so, thetubing 54 including recess 62 was expanded to final expanded diameter.When this happened, the sliding member 60 was released and theelastomeric sleeve 56 was allowed to return to its unstretcheddimensions.

As noted above, it is desirable for expandable tubing to reduce theannulus between the tubing string and the borehole wall as much aspossible. The tubing may be expanded only a limited amount withoutrupturing. It is therefore desirable for the tubing to have the largestpossible diameter in its unexpanded condition as it is run into theborehole. That is, the larger the tubing is before expansion, the largerit can be after expansion. Elements carried on the outer surface oftubing as it is run in to a borehole increase the outer diameter of thestring. The total outer diameter must be sized to allow the string to berun into the borehole. The total diameter is the sum of the diameter ofthe actual tubing plus the thickness or radial dimension of any externalelements. Thus external elements effectively reduce the allowablediameter of the actual expandable tubing elements.

In the embodiment of FIGS. 3 and 4, the total overall diameter ofexpandable tubing 54 as it is run into the borehole is reduced byprestretching elastomeric sleeve 56 into the shape shown in FIG. 3. Thereduction in radial dimension of sleeve 56 allows the tubing 54 to havea larger unexpanded diameter. As the tubing is expanded as illustratedin FIG. 4, the elastomeric sleeve 56 is allowed to return to itsoriginal shape in which it extends further radially from the tubing 54.As a result, when expansion cone 64 passes beneath elastomeric sleeve56, it will form an annular isolator in a larger borehole or anirregular borehole. The relaxed shape of sleeve 56 is selected so thatfor the largest expected diameter of borehole, the sleeve will contactthe borehole wall upon tubing expansion and be compressed radially withsufficient internal stress to form a good seal with the borehole wall.Upon radial compression, the sleeve 56 will expand or extrude to someextent axially along the annulus since the volume of the elastomerremains constant.

It is possible that the annular isolator of FIGS. 3 and 4 is positionedin a competent borehole which is at the nominal drilled size or is evenundersized due to swelling of the borehole wall on contact with drillingfluid. In such cases, the relaxed thickness of sleeve 56 may besufficient to contact the borehole wall 57 before expansion of tubing54. As the cone 64 passes under the sleeve 56, it would then need toexpand or extrude further axially to avoid excessive forces. Thispressure relief can occur in either of two ways. The sliding ring 60 canbe adapted so that, after expansion, it can slide on the expanded tubing54 at a preselected force level. Alternatively the ring 58 can beattached to the tubing 54 with a crimp or similar bond which releasesand allows limited movement at axial force above a preselected level. Ineither case, the maximum force exerted by the expansion of tubing 54under the sleeve 56 can be limited while maintaining a significantstress on the sleeve 56 to achieve a seal with a borehole wall. If ring58 is used as a pressure relief device, it is desirable to provide alocking mechanism to prevent further sliding after the expanding tool 64has passed through the ring 58. The locking device can be one or moreslip type teeth 59 on the ring 58 which will bite into the tubing 54when it expands under the ring 58. Other mechanisms may be used to allowlimited pressure relief while retaining sufficient stress in thecompressed sleeve 56 to maintain a good seal to a borehole.

In FIG. 5, there is illustrated a partially expanded expandable tubingsection 66. Section 66 carries fixed elastomeric sleeves 68 and 70 onits outer circumference. In this illustration, the borehole wall 72 isshown with an enlarged portion 74 at the location of elastomeric sleeve70. In this embodiment, an adjustable or variable diameter expandingcone 76 is employed to expand the tubing 66. As the tubing 66 isexpanded in the area of the enlarged area 74, the diameter of the cone76 has been increased to overexpand tubing 66 causing sleeve 70 to makea firm contact with borehole wall in region 74. In area 75 of boreholewall 72 which has not been enlarged, sleeve 68 will make contact withnormal expansion of tubing 66. The variable expansion cone 76 may beused in conjunction with a fixed expansion cone such as cone 48 of FIG.2 or cone 64 of FIG. 4. Both cones can be carried on one expansion toolstring, or the adjustable cone can be carried down hole with the tubingas it is installed and picked up by the expansion tool when it reachesthe end of the tubing string. After expansion of the tubing, screens,etc., by a fixed cone, the adjustable cone 76 may be used to furtherexpand the sections with external sleeves 70 to ensure making a sealwith the borehole. This can be done on a single trip into the borehole.For example, the fixed cone can expand the entire tubing string as thetool is run down the borehole and the adjustable cone can be deployed atdesired locations as the tool is run back up hole.

FIGS. 6, 7, 8 and 9 illustrate another embodiment having an externalelastomeric sleeve which has a variable radial dimension which isincreased before tubing is expanded. In FIGS. 6 and 7, an elastomericsleeve 80 is illustrated in its position as installed for running tubinginto a borehole. The sleeve 80 is connected at one end to a fixed ring82 on the tubing 78. The ring 82 holds the sleeve 80 in place. A slidingring 84 is connected to the other end of sleeve 80. Elastomeric sleeve80 is notched or grooved at 86 to generate hinge or flexing sections.

A second sleeve 88 is illustrated in two stages of deployment on theleft sides of FIGS. 6 and 7. Sleeve 88 was essentially identical tosleeve 80 when tubing 78 was run into a borehole. In FIG. 6, anexpansion tool 90 has moved into the left side of tubing 78 and expandeda portion of tubing 78 up to a sliding ring 92 connected to the left endof sleeve 88. As the expanding portion of tubing 78 contacts ring 92,the ring is pushed to the right and folds the sleeve 88 into theaccordion shape as illustrated. In the folded condition, the sleeve 88,has an increased radial dimension, i.e. it extends substantially fartherfrom the outer surface of tubing 78 than it did as installed for runningin. The sleeves 80, 88 may fold into shapes other than that shown inFIGS. 6 and 7. In alternative embodiments, the sleeves 80 and 88 may beunnotched or otherwise configured for folding and may simply becompressed by the sliding rings 84, 92 into a shape like that shown inFIG. 4. In FIG. 7, the expansion tool 90 has passed completely under thesleeve 88 and expanded the tubing 78 and expanded sleeve 88 so that thesleeve 88 has contacted a borehole wall at 94. The sliding ring 92 movedto the right until the sleeve 88 was completely folded and stoppedfurther movement of ring 92. At that point the tool 90 passed under thering 92, expanding it along with the tubing 78.

In FIGS. 8 and 9, means for holding sliding rings, such as rings 84 and92 in FIGS. 6 and 7, in place during installation of the tubing areillustrated. In FIGS. 8 and 9, an elastomeric sleeve 96 and fixed ring98 may be the same as parts 80 and 82 shown in FIGS. 6 and 7. In FIGS. 8and 9, expandable tubing 100 is provided with a recess 102 for holding asliding ring in place. In FIG. 8, a sliding ring 104 has a matchingrecess 106 near its center which extends into recess 102 to lock thesliding ring in place. In FIG. 9, a sliding ring 108 has an edge 110shaped to fit within recess 102. In both the FIG. 8 and FIG. 9embodiments, the recesses 102 will be removed or flattened as anexpansion cone is forced through expandable tubing 100. When thisoccurs, the sliding rings 104 and 108 will no longer be locked intoplace and will be free to slide along the expandable tubing 100 as it isexpanded. After tubing expansion, the elastomeric sleeve 96 in FIGS. 8and 9 may take the form of sleeve 88 shown in FIG. 7.

As noted above with reference to FIGS. 3 and 4, it is possible in asmall borehole that expansion of sleeve 88 as shown in FIG. 7 wouldresult in excessive pressure or force on the expansion tool. Pressurerelief can be provided in the same manner as discussed above. That is,the sliding ring 92 may be adapted to slide back to the left in responseto excessive pressure on the sleeve 88. Or the ring 90 can be connectedto tubing 78 with a crimp, like the arrangements shown in FIGS. 8 and 9,so that it releases and slides to the right if sufficient force isapplied.

With reference now to FIG. 10, an alternate embodiment in whichexpanding chemical materials are used to form an annular isolator isillustrated. In FIG. 10, expandable tubing 112 is essentially the sameas expandable tubing shown in the previous Figures. In this embodiment,two elastomeric rings 114 and 116, which may be essentially the same asrings 44 and 46 shown in FIG. 2, are carried on an outer surface of thetubing 112. Tubing 112 may have a fluid tight wall between the rings 114and 116 and may be perforated on the ends of the portion which isillustrated. Between elastomeric rings 114 and 116, there is provided acylindrical coating or sleeve 118 of various chemical materials carriedon the outer wall of tubing 112. In this embodiment, the layer 118includes solid particles of magnesium oxide and monopotassium phosphate120 encapsulated in an essentially inert binder 122, for example driedclay. The chemicals magnesium oxide and monopotassium phosphate willreact in the presence of water and liquefy. The liquid will then go to agel phase and eventually crystallize into a solid ceramic materialmagnesium potassium phosphate hexahydrate. This material is generallyknown as an acid-base cement and is sometimes referred to as achemically bonded ceramic. It normally hardens in about twenty minutesand binds well to a variety of substrates. Other acid-base cementsystems may be used if desired. Some require up to twenty-two waters ofhydration and may be useful where larger void spaces need to be filled.While this embodiment uses a material like clay as the encapsulatingmaterial 122, any other material or packaging arrangement whichseparates the individual chemical particles during installation oftubing 112 in a well bore and prevents liquids in the borehole fromcontacting chemical materials may be used. As disclosed below, theindividual chemical components may be encapsulated in microcapsules,tubes, bags, etc. which separate and protect them during installation oftubing in a bore hole.

Upon driving an expansion cone through the tubing 112 as illustrated inFIG. 2, the encapsulating material 122 is broken or crushed allowing thechemical materials 120 to mix with water in the borehole annulus andreact to form the solid material as discussed above. In this FIG. 10embodiment, the elastomeric rings 114 and 116 are used primarily to holdthe chemical reactants 120 in position until the chemical reaction hasbeen completed. As the reaction occurs, the volume of chemical materialsexpands by the reaction with and incorporation of water and the finalannular isolator is formed by the reacted chemicals. Thus, theelastomeric rings 114 and 116 are optional, but are preferred to ensureproper placement of the chemicals as they react. It is desirable thatthe rings 114 and 116 be designed to allow release of material in theevent the chemical reaction results in excessive pressure which mightdamage the tubing 112. In many cases it may be desirable for one or bothof the rings 114, 116 to be sized to not form a total seal with theborehole. This will allow additional water and other annular fluids toflow into the area to provide waters of hydration. With such a loosefit, the rings 114 and 116 will diminish outflow of more viscousmaterials such as the gel at lower pressures, while allowing some flowof more fluid materials or of the gel at excessive pressures. Ifdesired, the chemicals may be encapsulated in a heat sensitive materialand released by running a heater into the tubing 112 to the desiredlocation.

Also illustrated in FIG. 10 is a conduit 115 passing through the rings114, 116 and the chemical coating 118. This conduit 115 is provided forpower, control, communication signals, etc. like conduit 45 discussedabove with reference to FIG. 2. In this embodiment, the conduit 115 willbe imbedded in the acid base cement after it sets to form an annularisolator. Many of the advantages of this described embodiment areachieved regardless of the presence or absence of the conduit 115.

FIG. 11 illustrates another embodiment using various chemical materialsfor forming an annular isolator. An expandable tubing section 124preferably carries a pair of elastomeric rings 126 and 128. Between thelocations of rings 126 and 128, the tubing 124 has an annular recessedarea 130. Within the recess 130 is carried a swellable polymer 132 suchas cross-linked polyacrylamide in a dry condition. A rupturable sleeve134 is carried on the outer wall of tubing 124 extending across therecessed section 130. The space between sleeve 134 and recessed section130 defines a compartment for carrying a material for forming an annularisolator, i.e. the swellable polymer 132. The sleeve 134 protects theswellable polymer 132 from fluids during installation of the tubing 124into a borehole. The material 132 may be in the form of powder or fineor small particles which are held in place by the sleeve 134. Thematerial 132 may also be made in solid blocks or sheets which mayfracture on expansion. It may also be formed into porous or spongysheets. If solid or spongy sheet form is used, the sleeve 134 may not beneeded or may simply be a coating or film adhered to the outer surfaceof the material 132. When an expansion cone is forced through the tubing124, the reduced diameter portion 130 is expanded along with the rest oftubing 124 to the final designed expanded diameter. Rubber rings 126 and128 will be expanded to restrict or stop annular flow. The protectivesheath 134 is designed to split or shatter instead of expanding thusexposing the polymer 132 to fluids in the wellbore. Polymer 132 willabsorb large quantities of water and swell to several times its initialvolume. The material 132 at this point will have been forced outside thefinal diameter of the tubing 124 and thereby into contact with theborehole wall. The combination of the swellable polymer and theelastomeric seals 126 and 128 forms an annular isolator. The annularisolator thus formed remains flexible and will conform to unevenborehole shapes and sizes and will continue to conform if the shape orsize of the borehole changes.

Various other solid, liquid or viscous materials can be used as thechemical materials 132 in the FIG. 11 embodiment. The swellable polymermay be formed into sheets or solid shapes which may be carried on thetubing 124. The acid-base cement materials used in the FIG. 10embodiment could be carried within the recess 130 and protected by thesheath 134 during installation of the tubing 124. As discussed withreference to FIG. 10, the elastomeric rings 126 and 128 are optional,but preferred to hold materials in place while reactions occur and arepreferably designed to limit the amount of pressure that can begenerated by the swelling materials.

With reference now to FIG. 12, there is illustrated another embodimentof the present invention in which a fluid may be used to inflate asleeve. In FIG. 12, expandable tubing 136 is formed with a reduceddiameter portion 138 providing a recess in which a flowable annularisolator forming material 140 may be stored. An outer inflatable metalsheath or sleeve 142 forms a fluid tight chamber or compartment with thereduced diameter section 138. This sheath 142 as installed has an outerdiameter greater than the expandable member 136 to increase the amountof material 140 which may be carried down hole with the tubing 136. Theouter sheath 142 is bonded by welding or otherwise to the tubing 136 atup hole end 144. At its down hole end 146, the sheath 142 is bonded tothe tubing 136 with an elastomeric seal 148. A retainer sleeve 150 hasone end welded to the tubing 136 and an opposite end extending over end146 of the outer sleeve 142. The retainer sleeve 150 preferably includesat least one vent hole 152 near its center. A portion 143 of outersleeve 142 is predisposed to expand at a lower pressure than theremaining portion of sleeve 142. The portion 143 may be made of adifferent material or may be treated to expand at lower pressure. Forexample, the portion 143 may be corrugated and annealed before assemblyinto the form shown in FIG. 11. Portion 143 is preferably adjacent theend 146 of sleeve 142 which would be expanded last by an expansion tool.The metallic outer sleeve 142 may be covered by an elastomeric sleeve orlayer 154 on its outer surface. An elastomeric sleeve 154 is preferredon portion 143 if it is corrugated to help form a seal with a boreholewall in case the corrugations are not completely removed during theexpansion process. The elastomeric sleeve 154 would also be preferred onany portion of the sleeve 142 which is perforated.

The inflatable sleeve 142 and other inflatable sleeves discussed beloware referred to as “metal” sleeves or sheaths primarily to distinguishfrom elastomeric materials. They may be formed of many metallic likesubstances such as ductile iron, stainless steel or other alloys, or acomposite including a polymer matrix composite or metal matrixcomposite. They may be perforated or heat-treated, e.g. annealed, toreduce the force needed for inflation.

In operation, the embodiment of FIG. 12 is run into a wellbore in thecondition as illustrated in FIG. 12. Once properly positioned, anexpander cone is forced through the tubing 136 from left to right asillustrated in FIG. 2. When the cone reaches the reduced diametersection 138 and begins expanding it to the same final diameter as tubing136, the pressure of material 140 is increased. As pressure increases,the outer sleeve 142 is inflated outwardly towards a borehole wall.Inflation begins with the portion 143 which inflates at a first pressurelevel. When the portion 143 contacts a borehole wall, the pressure ofmaterial 140 increases until a second pressure level is reached at whichthe rest of outer sleeve 142 begins to inflate. If proper dimensionshave been selected, the inflatable outer sleeve 142 and elastomericlayer 154 will be pressed into conforming contact with the boreholewall. To ensure that such contact is made, it is desirable to have anexcess of material 140 available. If there is excess material and theouter sleeve 142 makes firm contact with an outer borehole wall over itswhole length, the expansion process will raise the pressure of material140 to a third level at which the polymeric seal 148 opens and releasesexcess material. The excess material may then flow through the vent 152into the annular space between tubing 136 and a borehole wall. When theexpander cone has moved to the end 146 of the outer sleeve 142, tubing136 and the outer sleeve 142 will be expanded against the overlappingportion of the retainer sleeve 150. As these parts are all expandedtogether, a seal is reformed preventing further leakage of material 140from the space between the tubing 136 and the outer sleeve 142. Thematerial 140 may be any of the reactive or swellable materials disclosedherein so that the extra material vented at 152 may react, e.g. withambient fluids, to form an additional annular isolator between thetubing 136 and the borehole wall.

In the FIG. 12 embodiment, the outer sleeve 142 is shown to have anexpanded initial diameter to allow more material 140 to be carried intothe borehole. As discussed above, this arrangement results in a smallermaximum unexpanded diameter of tubing 136. It would be possible to forma fluid compartment or reservoir with only the outer sleeve 142, that iswithout the reduced diameter tubing section 138. However, to achieve thesame volume of stored fluid, the sleeve 142 would have to extend fartherfrom tubing 136 and the maximum unexpanded diameter of tubing 136 wouldbe further reduced.

FIG. 13 illustrates an alternative embodiment which allows a greaterunexpanded diameter of an expandable tubing 156. In this embodiment, anouter sleeve 158 has a cylindrical shape and has essentially the sameouter diameter as the tubing 156. Otherwise, the outer sleeve 158 issealed to the tubing 156 in the same manner as the outer sleeve 142 ofFIG. 11. Likewise, this embodiment includes a pressure reliefarrangement 157 which may be identical to the one used in the FIG. 12embodiment. The sleeve 158 preferably has a portion 159 predisposed toexpand at a lower pressure than the remaining portion of sleeve 158,like the portion 143 of outer sleeve 142 of FIG. 12. Sleeve 158 maycarry an outer elastomeric sleeve like sleeve 154 in FIG. 12.

In order to provide storage space for a larger volume of annularisolator forming material in the FIG. 13 embodiment, a reduced diameterportion 160 of tubing 156 is corrugated as illustrated in FIG. 14. It ispreferred that the portion 160 be formed from tubing having a largerunexpanded diameter than the unexpanded diameter of tubing 156. Duringcorrugation of the portion 160, the tubing wall may be stretched to havea larger total circumference after corrugation and then annealed torelieve stress. Each of these arrangements helps reduce total stressesin the section 160 which result from unfolding the corrugations andexpanding to final diameter. As can be seen from FIG. 14, the crimpingor corrugation of the section 160 of tubing 156 produces relativelylarge spaces 162 for storage of expansion fluid. When an expansion coneis run through the tubing in the embodiment of FIG. 13, the corrugationsare unfolded driving the materials in spaces 162 to inflate the outersleeve 158 in the same manner as described with respect to FIG. 12.Except for the unfolding of the corrugated section 160, the embodimentof FIG. 13 operates in the same way as the FIG. 12 embodiment. That is,as an expansion tool moves through tubing 156 from left to right,material 162 reaches a first pressure level at which sleeve section 159expands until it contacts a borehole wall. Then the material reaches asecond pressure level at which the rest of sleeve 158 expands. If thewhole sleeve 158 contacts the borehole wall, a third pressure level isreached at which the relief valve arrangement 157 vents excess materialinto the annulus.

The pressure relief arrangements shown in FIGS. 12 and 13, and in manyof the following embodiments, are preferred in expandable tubing systemswhich use a fixed diameter cone for expansion. It is often desirablethat the inner diameter of an expandable tubing string be the samethroughout its entire length after expansion. Use of a fixed diameterexpansion tool provides such a constant internal diameter. The pressurerelief mechanism provides several advantages in such systems. It isdesirable that a large enough quantity of expansion material be carrieddown hole with the expandable tubing to ensure formation of a goodannular isolator in an oversized, e.g. washed out, and irregularlyshaped portion of the borehole. If the borehole is of nominal size orundersized, there will then be more fluid than is needed to form theannular isolator. If there were no pressure relief mechanism, excessivepressure could occur in the material during expansion and the expansiontool could experience excessive forces. The result could be rupturing ofthe tubing or stoppage or breaking of the expansion tool. The pressurerelief mechanisms release the excess material into the annulus to avoidexcess pressures and forces, and, with use of proper materials, act asadditional annular isolators.

FIGS. 15 and 16 illustrate another embodiment of the present inventionin which a material carried with expandable tubing as installed in aborehole is used to inflate an annular isolator. In FIG. 15, anexpandable tubular member 164 includes a reduced diameter section 166providing a compartment for storage of an isolator forming material,preferably a fluid 168. The fluid 168 is held in place by an elastomericsleeve 170 which completely covers the fluid 168 and extends asubstantial additional distance along the outer surface of theexpandable tubing 164. A first section of perforated metallic shroud 172is connected at a first end 174 to the expandable tubing 164. The shroud172 extends around the elastomeric sleeve 170 for a distance at leastequal to the length of the reduced diameter section 166 of the tubing164. A second section of shroud 176 has one end 178 connected to thetubular member 164. Shroud 176 covers and holds in place one end of theelastomeric sleeve 170. Between shroud section 172 and 176, a portion ofthe elastomeric sleeve 170 is exposed. The shroud section 176 and aportion 180, adjacent the exposed portion of sleeve 170, of shroud 172are highly perforated and therefore designed to expand relativelyeasily. The remaining portion 182 of shroud 172 has only minimalslotting (or in some embodiments no slotting) and requires greaterpressure to expand. If desired, both shroud sections 172 and 176 may becovered by a second elastomeric sleeve to improve sealing between aborehole wall and the shrouds after they are expanded.

FIG. 16 illustrates the condition of this embodiment after an expandercone has been driven through the expandable tubing 164 from left toright in FIGS. 15 and 16. As the forcing cone moves through the tubing164, the fluid 168 is first forced to flow under the exposed portion ofthe elastomeric sleeve 170. As illustrated in FIG. 16, it will expanduntil it contacts and conforms to a borehole wall 184. In thisembodiment, it is preferred that the reduced diameter section 166 of thetubing 164 be considerably longer than the exposed portion of the rubbersleeve 170. By a proper selection of the ratio of these lengths,sufficient material 168 is available to provide a very large expansionof the rubber sleeve 170. As the elastomeric sleeve 170 expands intocontact with the borehole wall, the pressure of fluid 168 increases andthe highly perforated shroud portions 176 and 180 will expand also. Ifadditional fluid is available after expansion of highly perforatedshroud portions 176 and 180 into contact with the borehole wall, thefluid pressure will rise sufficiently to cause expansion of theminimally perforated portion 182 of the shroud 172. The slotting ofportion 182 therefore provides a pressure relief or limiting function.It is also desirable to include a relief mechanism as shown in FIGS. 12and 13 to provide an additional pressure limiting mechanism, in case theborehole is of nominal size or undersized.

With reference now to FIGS. 17, 18, and 19, there is shown an annularisolator system which provides pre-compression of an externalelastomeric sleeve before expansion of the tubing on which the sleeve iscarried. In FIG. 17, expandable tubing 190 is shown having beenpartially expanded by an expansion tool 192 carried on a pilot expansionmandrel 194. In FIG. 17, the expanded portion 196 may carry an externalscreen expanded into contact with a borehole wall 198. To the right ofthis expanded portion is provided a threaded joint between expandabletubing sections 200 and 202. An elastomeric sleeve 204 is carried on theouter diameter of portion 200. The threaded portion 202 is connected toa reduced diameter section 206 of the expandable tubing into which aportion 208 of the expansion mandrel 194 has been pushed to form aninterference fit. The mandrel portion 208 is preferably splined on itsouter surface to form a tight grip with reduced diameter section 206. Arotating bearing 210 is provided between the elastomeric sleeve 204 andthe lower tubing section 202.

After the tubing string 190 has been expanded to the point shown in FIG.17, the expansion mandrel 194 is rotated so that its splined end 208causes rotation of tubing section 202 relative to section 200. As aresult of the threaded connection, the elastomeric member 204 iscompressed axially so that its radial dimension is increased asillustrated in FIG. 18.

Once the elastomeric sleeve 204 has been expanded as illustrated in FIG.18, the expansion cone 192 may be forced through the tubing string 190past the tubing sections 200 and 202 expanding all the sections to finaldiameter and driving elastomeric sleeve 204 into engagement withborehole wall 198 as shown in FIG. 19. As the tubing string 190 isexpanded, the threaded connection between sections 200 and 202 arefirmly bonded together to prevent further rotation.

With reference to FIG. 20, an alternative form of the embodiment ofFIGS. 17, 18 and 19 is illustrated. In this embodiment the sameexpansion tool including expansion cone 192, mandrel 194 and splined end208 may be used. Two expandable tubing sections 209 and 210 areconnected by an internal sleeve 211. The sleeve 211 has external threadson each end which mate with internal threads on sections 209 and 210.The sleeve has an external flange 212 and an internal flange 213 nearits center. An elastomeric sleeve 214 is carried on sleeve 211 betweenthe external flange 212 and the tubing section 209. The internal flange213 is sized to mate with the splined end 208 of mandrel 194. This FIG.20 system operates in essentially the same way as the system shown inFIGS. 17, 18 and 19. As the expansion cone 192 is passing through andexpanding the tubing section 209, the splined end 208 engages theinternal flange 213. Expansion cone downward movement is stopped andmandrel 194 is rotated to turn the sleeve 211 relative to both tubingsections 209 and 210. As sleeve 211 turns, it moves the external flange212 away from tubing section 210 and towards section 209 axiallycompressing the elastomeric sleeve 214 between the flange 212 and theend of tubing section 209. The sleeve 214 will increase in radialdimension as illustrated in FIG. 18. Then the expansion cone may bedriven through the rest of tubing 209, the sleeve 211 and the tubing 210to expand the tubing and force the elastomeric sleeve 214 outward towarda borehole wall to close off the annulus as illustrated in FIG. 19.

With reference now to FIGS. 21, 22 and 23, there is illustrated anembodiment of the present invention in which a coil spring is used toexpand an external elastomeric sleeve to form an annular isolator. InFIG. 21, an elastomeric sleeve 220 is illustrated in its relaxed ornatural shape as it would be originally manufactured. sleeve 220 is madeup of two parts. It includes a barrel shaped elastomeric sleeve 222.That is, the sleeve 222 has a diameter at each end corresponding to theouter diameter of an unexpanded tubular member and a larger diameter inits center. Embedded within the elastomeric sleeve 222 is a coil spring224 having generally the same shape in its relaxed condition. In FIG.22, the sleeve 220 is shown as installed on a section of unexpandedexpandable tubing 226 for running into a borehole. The member 220 hasbeen stretched lengthwise causing it to conform to the outer diameter ofthe tubing 226. The sleeve 220 may be held onto the tubing 226 by afixed ring 228 on its down hole end and a sliding ring 230 on its uphole end. The rings 228 and 230 may be essentially the same as the rings58 and 60 illustrated in FIG. 3. Sliding ring 230 would be releasablylatched into a recess formed on the outer surface of expandable tubing226 to keep the sleeve 220 in its reduced diameter shape for runninginto the tubing in the same manner as shown in FIG. 3.

FIG. 23 illustrates the shape and orientation of the elastomeric sleeve220 after the tubing 226 has been placed in an open borehole 232 and anexpansion cone has been driven through the tubing 226 from left toright. As illustrated in FIG. 4, the expansion cone expands the tubing226 including a recess holding sliding ring 230 which releases thesliding ring 230 and allows the sleeve 220 to return to its naturalshape shown in FIG. 21. Upon thus expanding, the sleeve 220 contacts theborehole wall 232 forming an annular isolator.

With reference to FIGS. 24 and 25, there is illustrated a systemincluding an external elastomeric bladder which is inflated by fluid inconjunction with expansion of expandable tubing section 240. Anexpandable bladder 242 is carried on the outside of the expandabletubing 240. Also carried on the outside of tubing 240 is an annularfluid chamber 244. In one end of chamber 244 is a fluid 246 and in theother end is a compressed spring 248. Between the fluid 246 and spring248 is a sliding seal 250. A spring retainer 252 within the chamber 244holds the spring 248 in a compressed state by means of a release weld254. A port 256 between the chamber 244 and the bladder 242 is initiallysealed by a rupture disk 258.

In FIG. 25, an expansion cone 260 is shown moving from right to leftexpanding the tubing 240. As the release weld 254 is expanded, it breaksfree from spring retainer 252 releasing the spring 248 to drive thesliding piston 250 to the left which injects the fluid 246 through therupture disk 258 into the bladder 242. The bladder 242 is thus expandedbefore the expansion cone 260 reaches that part of the expandable tubing240 which carries the bladder 242. As the expansion cone continues fromright to left and expands the tubing 240, it further drives the inflatedbladder 242 in firm contact with borehole wall 262.

In a preferred embodiment, the bladder 242 is partly filled with achemical compound 245 which will react with a chemical compound 246carried in chamber 244. When the compound 246 is driven into the bladder242, the two chemical parts are mixed and they react to form a solid orsemi-solid plastic material and/or expand.

In the FIGS. 24, 25 embodiment, the spring 248 can be replaced withother stored energy devices, such as a pneumatic spring. This embodimentcan also be operated without a stored energy device. For example, thespring 248, retainer 252 and the piston 250 may be removed. The entirevolume of chamber 244 may then be filled with fluid 246. As theexpansion cone 260 moves from right to left, it will collapse thechamber 244 and squeeze the fluid 246 through port 256 into the bladder242. The bladder would be filled before the cone 20 moves under it andexpands it further as tubing 240 is expanded.

It is desirable to provide a pressure relief or limiting arrangement inthe FIGS. 24, 25 embodiment. If the bladder 242 is installed in anominal or undersized portion of a borehole, it is possible thatexcessive pressure may be experienced as the expansion cone passes underthe bladder. In the above described embodiment in which the chamber 244is filled with fluid and no spring is used, the outer wall of chamber244 may be designed to expand at a pressure low enough to prevent damageto the bladder 242 or the expansion tool 260. A pressure relief valvemay also be included in the chamber 244 to vent excess fluid if thechamber 244 itself expands into contact with a borehole wall.

With reference now to FIG. 26, there is illustrated an expandable tubingsection 266 on which is carried a compressed open cell foam sleeve 268which may be expanded to form an annular isolation device. The foam 268is a low or zero permeability open cell foam product which restrictsflow in the annular direction. It is elastically compressible to atleast 50% of it initial thickness and reversibly expandable to itsoriginal thickness. Before running the tubing 266 into a well, the foamsleeve 268 is placed over the tubing and compressed axially and held inplace by a cage 270 formed of a series of longitudinal members 272connected by a series of circular rings 274. The cage 270, or at leastthe rings 274, are formed of a brittle or low tensile strength materialwhich cannot withstand the normal expansion of tubing 266 which occurswhen an expansion cone passes through the tubing. Therefore, as thetubing is expanded, for example as illustrated in FIG. 2, the cage 270fails and releases the foam 268 to expand to its original thickness orradial dimension. As this is occurring, the tubing 266 itself isexpanded pressing the foam 268 against the borehole wall to form anannular isolator.

The foam 268 may be made with reactive or swellable compounds carried indry state within the open cells of the foam. For example, the componentsof an acid-base cement as discussed with Reference to FIG. 10 or thecross-linked polyacrylamide discussed above with reference to FIG. 11,may be incorporated into the foam. A protective sleeve like sleeve 134of FIG. 11 may be used to protect the chemicals from fluid contactduring installation. After expansion of the tubing 266, the chemicalswould be exposed to formation fluids and react to form a cement orswellable mass to obtain structural rigidity and impermeability of theexpanded foam.

Other mechanisms may be used to compress the foam 268 as the tubing 266is run into a borehole. For example, helical bands or straps connectedto the tubing 266 at each end of the foam sleeve could be used. The endconnections could be arranged to break on expansion, releasing the foam268. Alternatively, the foam 268 could be covered by a vacuum shrunkplastic film. Such a film could also protect chemicals incorporated intothe foam 268 prior to expansion. The plastic film can be prestretched toits limit, so that upon further expansion by a tubing expansion tool,the film splits, releasing the foam 268 to expand and exposing chemicalsto the ambient fluids.

With reference now to FIG. 27 there is illustrated an annular isolatorsystem using a chemical reaction to provide power to forcibly drive asleeve into an expanded condition. A section of expandable tubing 280carries a sleeve 282 on its outer surface. One end 284 of the sleeve 282is fixed to the tubing 280. On the other end of the sleeve 282 isconnected a cylindrical piston 286 carried between a sleeve 288 and thetubing 280. On the end of piston 286 is a seal 290 between the piston286 and the sleeve 288 on one side and the expandable tubing 280 on theother side. The sleeve 282 may be elastomeric or metallic or may be anexpandable metallic sleeve with an elastomeric coating on its outersurface. Two chemical chambers 292 and 294 are formed between a portionof the sleeve 288 and the expandable tubing 280. A rupture disk 296separates the chemical chamber 292 from the piston 286. A frangibleseparator 298 separates the chemical chamber 292 from chamber 294.

In operation of the FIG. 27 embodiment, an expansion cone is driven fromleft to right expanding the diameter of the tubing 280. As the expansionreaches the separator 298, the separator is broken allowing thechemicals in chambers 292 and 294 to mix and react. In this embodiment,the chemicals would produce a hypergolic reaction generatingconsiderable force to break the rupture disk 296 and drive the piston286 to the right in the figure. When this happens, the sleeve 282 willbuckle and fold outward to contact the borehole wall 300. As a forcingcone passes under the sleeve 282, it will further compress the sleeve282 against borehole wall 300 forming an annular isolator.

With reference to FIGS. 28 and 29, there is illustrated an embodiment ofthe present invention using petal shaped plates to form an annularisolator. In FIG. 29, there is illustrated the normal or free-stateposition of a series of plates 310 carried on an expandable tubingsection 312. Each plate has one end attached to the outer surface oftubing 312 along a circumferential line around the tubing. The platesare large enough to overlap in the expanded condition shown in FIG. 29.Together the plates 310 form a conical barrier between the tubing 312and a borehole wall. For running into the borehole, the plates 310 arefolded against the tubing 312 and held in place by a strap 314. Thestrap or ring 314 is made of brittle material which breaks upon anysignificant expansion. As an expansion cone is driven through the tubing312 from left to right, the strap 314 is broken, releasing the plates310 to expand back toward their free state position like an umbrella orflower until they contact a borehole wall. One or more sets of theplates 310 may be used in conjunction with other embodiments of thepresent invention such as those shown in FIGS. 10 and 11. The plates 310may be used in place of the annular elastomeric rings 114, 116, 126 and128 shown in those figures. The plates 310 may be made of metal and maybe coated with an elastomeric material to improve sealing between theindividual plates and between the plates and the borehole wall.Alternatively, the plates may be permeable to fluids, but impermeable togels or to particulates. For example, permeable plates may be used totrap or filter out fine sand occurring naturally in the annulus or whichis intentionally placed in the annulus to form an annular isolator.

Many of the embodiments illustrated in previous figures carry annularisolator forming material on the outer surface of expandable tubing. Thematerial may be a somewhat solid elastomeric material or a fluidmaterial which is injected into the annular space between a section oftubing and a borehole wall to form an annular isolator. To the extentsuch materials are carried on the external surface of expandable tubing,the overall diameter of the tubing itself must typically be reduced toallow the tubing to be run into a borehole. In addition, any materialcarried on the outside surface of the tubing are subject to damageduring installation in a borehole.

With reference to FIG. 30, there is illustrated an embodiment in whichthe annular isolator forming material is carried on the inner surface ofan expandable tubing section. In FIG. 30 is shown a section 320 ofexpandable tubing in its unexpanded condition. On the inner surface oftubing 320 is carried a cylindrical sleeve 322 attached at each end tothe inner surface of tubing 320. The space between sleeve 322 and thetubing 320 defines a compartment in which is carried a quantity ofisolator forming material 324. The inner sleeve 322 may be of anydesired length, preferably less than one tubing section, and may thuscarry a considerable quantity of material 324. One or more ports 326 areprovided through expandable tubing section 320 near one end of the innersleeve 322. The ports 326 should be positioned at the end opposite theend of sleeve 322 which will be first contacted by an expansion tool.Port 326 preferably includes a check valve which allows material to flowfrom the inside of tubing 320 to the outside, but prevents flow from theoutside to the inside. If desired, various means can be provided tolimit the annular flow of material 324 after it passes through the ports326. Annular elastomeric rings 328 may be placed on the outer surface oftubing 320 to limit the flow of the material 324. Alternatively, anexpandable bladder 330 may be attached to the outer surface ofexpandable tubing 320 to confine material which passes through the ports326. The expandable bladder 330 may be formed of an expandable metalsleeve or elastomeric sleeve or a combination of the two.

In operation, the embodiment of FIG. 30 will be installed in an openborehole at a location which needs an annular isolator. An expansioncone is then driven through expandable tubing 320 from left to right.When the expansion cone reaches the inner sleeve 322, the sleeve 322 isexpanded against the inner wall of tubing 320 applying pressure tomaterial 324 which then flows through the ports 326 to the outer surfaceof expandable tubing 320. Alternatively, the sleeve 322 may be designedso that the ends of sleeve 322 slide on or are torn away from the innersurface of tubing 320 by the expansion cone. As the cone moves, it cancompress the sleeve and squeeze the material 324 through the ports 326.The compressed inner sleeve 322 would then be forced down hole with theexpansion tool. If the outer sleeve 330 is used, the material 324 may beany type of liquid, gas, or liquid like solid (such as glass or otherbeads) which will inflate the sleeve 330 to form a seal with theborehole wall. If sleeve 330 is used, it is preferred to provide apressure relief mechanism like arrangement 157 shown in FIG. 13. If thesleeve 330 is not used, the material 324 may be any liquid orliquid/solid mix that will solidify or have sufficient viscosity that itwill stay where placed, or reactive materials such as acid-base cementor cross linked polyacrylamide taught with reference to FIGS. 10 and 11above which may be injected through the port 326 to contact boreholefluids and form an annular isolator. If the rings 328 are used tocontrol positioning of reactive materials, it is preferred that therings 328 be designed to limit the maximum pressure of such reactivematerials.

For many of the above described embodiments it is desirable that thefluid placed in the annulus to form an isolator be very viscous or beable to change properties when exposed to available fluids in the wellannulus. Thixotropic materials which are more viscous when stationarythan when being pumped may also provide advantages. Various siliconematerials are available with these desirable properties. Some are curedby contact with water and become essentially solid. With furtherreference to FIG. 30, such a condensate curing silicone material may beinjected into the annulus without use of the sleeve 330 and with orwithout the use of rings 328. Such a curable viscous silicone materialwill conform to any formation wall contour and will fill micro fracturesand porosity some distance into the borehole wall which may causeleakage past other types of isolators. This type of curable siliconematerial may also provide advantages in the embodiments illustrated inFIGS. 11, 12, 13 and 35. In the FIGS. 12 and 13 embodiments, such amaterial provides a good material for inflating the sleeves 154 and 158and any excess fluid vented into the annulus will cure and form a solidisolator.

With reference now to FIG. 31, another embodiment which allows maximumdiameter of the expandable tubing as run is illustrated. A section ofexpandable tubing 336 has a reduced diameter section 338. Within thereduced diameter section 338 are several ports 340 each preferablyincluding a check valve allowing fluid to flow from inside the tubing336 to the outside. On the outer surface of the tubing 336 in thereduced diameter section 338 is carried an inflatable bladder 342 sealedat each end to the tubing 336. Bladder 342 is preferably an elastomericmaterial. Since bladder 342 is carried on the reduced diameter section338, its uninflated outer diameter is no greater than the outer diameterof tubing 336. An expansion cone tool 344 is shown expanding tubing 336from left to right. On the expansion tool 344 mandrel 346 are carriedexternal seals 348 sized to produce a fluid tight seal with the innersurface of the reduced diameter section 338 of the tubing 336. Themandrel 346 includes ports 345 from its inner fluid passageway to itsouter surface. When the expansion tool 344 reaches the point illustratedin FIG. 31, the seals 348 form a fluid tight seal with the inner surfaceof reduced diameter tubing section 338. When that happens, pressurizedfluid within the expansion tool 344 flows through the side ports 345 onmandrel 346 and the tubing ports 340 to inflate the rubber bladder 342.As expansion of the tubing 336 is continued, the reduced diameter zone338 is expanded out to full diameter and the now inflated bladder 342 isforced firmly against the borehole wall to form an annular isolator.

In a simpler version of the FIG. 31 embodiment, the expandable bladder342 may be replaced with one or more solid elastomeric rings. Forexample two or more of the rings shown in FIG. 2 may be mounted in therecess 338. The benefit of larger unexpanded tubing diameter is achievedby this arrangement. The ports 340 may be eliminated or may be used toinject a fluid, preferably reactive, into the annulus between the ringsbefore or after expansion of tubing 336.

With reference to FIG. 32, there is illustrated an embodiment of thepresent invention which provides for over expansion of an expandabletubing member to form an annular isolator. In FIG. 32, an expandabletubing 356 is shown in place within a borehole 358. The expandabletubing 356 carries an elastomeric sleeve 360 on its outer surface. Inplace of the sleeve 360, several elastomeric rings such as shown in FIG.2 may be used if desired. A pressure expansion tool 362 is shown havingbeen run in from the surface location to the location of the sleeve 360.The tool 362 includes seals 364 which form a fluid tight seal with theinner wall of tubing 356. The tool 362 includes side ports 366 locatedbetween seals 364. It preferably includes a pressure relief valve 367.After the expansion tool 362 is positioned as shown, fluid is pumpedfrom the surface into the tool 362 at sufficient pressure to expand andoverexpand the tubing 356. When the elastomeric sleeve 360 contacts theborehole wall 358 an increase in pressure will be noted and expansioncan be stopped. The relief valve limits the pressure to avoid rupturingthe tubing 356. The tool 362 may be moved on through the tubing 356 toother locations where external sleeves such as 360 are carried andexpand them into contact with the borehole wall 358 to form otherannular isolators.

The expansion system shown in FIG. 32 may be used either before or afternormal expansion of the tubing 356. If it is performed before normalexpansion, the tool 362 may carry an adjustable expansion cone or maypick up a cone from the bottom of the tubing string for expansion as thetool 362 is withdrawn from the tubing 356. If performed after normalexpansion of the tubing 356, the seals 364 may be inflatable sealsallowing isolation of the zones which need over expansion after thenormal expansion process is performed.

With reference to FIGS. 33 and 34, a system for over expansion ofexpandable tubing using hydroforming techniques is illustrated. In FIG.33, a section of expandable tubing 370 carrying an elastomeric sleeve372 on its outer surface is illustrated. In order to expand the annularbarrier area 372, a pair of slips 374 are positioned on the inside oftubing 370 on each side of the barrier 372. Forces are then applieddriving the slips towards one another and placing the portion of tubing370 under the rubber sleeve 372 in compression. The axial compressionreduces the internal pressure required to expand tubing 370 and allowsit to expand to a larger diameter without rupturing. The pressure withinthe tubing 370 may be then raised to expand the section which is inaxial compression caused by the slips 374. As a result of the axialloading and the internal pressure, the tubing will expand as shown inFIG. 34 until the rubber sleeve 372 contacts the borehole wall 376. Thiswill cause an increase of pressure which indicates that an annularisolator has been formed. The slips 374 may then be released and movedto other locations for expansion to form other annular isolators. Ifdesired, the expansion tool shown in FIG. 32 may be used in conjunctionwith the slips shown in FIGS. 33 and 34 so that the expansion pressuremay be isolated to the annular barrier area of interest. A conduit 378may be positioned through the rubber sleeve 372 for providing power,control, communications signals, etc. to and from down hole equipment asdiscussed above with reference to conduit 45 in FIG. 2.

With reference to FIG. 35, there is illustrated an embodiment of thepresent invention which allows formation of a conforming annularisolator after expansion of expandable tubing. In FIG. 35, there isillustrated a section of expandable tubing 380 positioned within an openborehole 382. The tubing 380 carries a pair of elastomeric rings 384 and386. This is the same arrangement as illustrated in FIG. 2. Afterexpansion of the tubing 380 using a conventional expansion cone, it isseen that the expansion ring 386 has been compressed between theborehole wall 382 and the tubing 380 to form a seal while the expansionring 384 may not be tightly sealed against the borehole wall since ithas been expanded into an enlarged portion of the borehole 382. It isdesirable that the rings 384 and 386 be designed to limit the pressureof injected materials. Expanded tubing 380 includes one or more ports388 which may preferably include check valves. A fluid injection string390 which may be similar to the device 362 shown in FIG. 32, is shown inplace within expanded tubing 380. Injection string 390 includes seals392 on either side of a port 394 through the injection tool 390. Withthe injection tool 390 in position as illustrated, various annularisolator forming materials may be pumped from the surface through ports394 and 388 into the annular space between expanded tubing 380 and theborehole wall 382. The elastomeric rings 384 and 386 tend to keep theinjected material from flowing along the annulus. A conduit 394 may bepositioned through the rings 384 and 386 for providing power, control,communications signals, etc. to and from down hole equipment asdiscussed above with reference to conduit 45 in FIG. 2.

In the embodiment of FIG. 35, various materials may be pumped to formthe desired annular isolator. Chemical systems of choice would be thosewhich could be injected as a water thin fluid and then attain efficientviscosity to isolate the annulus. Such chemical systems include sodiumsilicate systems such as those used in the Angard™ and Anjel® servicesprovided by Halliburton Energy Services. Resin systems such as thosedisclosed in U.S. Pat. No. 5,865,845 (which is hereby incorporated byreference for all purposes) owned by Halliburton and those used in theResSeal™, Sanfix®, Sanstop™ or Hydrofix™ water shutoff systems providedby Halliburton would also be useful. Crosslinkable polymer systems suchas those provided in Halliburton's H2Zero™ and PermSeal™ services wouldalso be suitable. Emulsion polymers such as those provided inHalliburton's Matrol™ service may also create a highly viscous gel inplace. Various cements may also be injected into the annulus with thissystem. The system of FIG. 35 is particularly useful if the surroundingformation has excessive porosity. The injected fluid may be selected topenetrate into the formation away from the borehole wall 382 to preventfluids from bypassing the annular isolator by flowing through theformation itself.

The petal plate embodiment of FIGS. 28 and 29 may be used in place ofthe rings 384 and 386 shown in FIG. 35. They may be particularly usefulfor forming a annular isolator using fine sand as annular isolationmaterial. A premixed slurry of fine sand can be pumped outside tubing380 between a pair of the petal plate sets 310. The plates 310 shouldfilter out and dehydrate the sand as pressure is increased. It isbelieved that such a sand pack several feet long would provide a goodannular isolator blocking the annular flow of produced fluids. Thisembodiment may also form a sand annular isolator by catching orfiltering out naturally occurring sand which is produced from theformations and flows in the annulus.

With reference to FIG. 36, there is illustrated another system forpreexpanding an externally carried elastomeric sleeve of the type shownin FIGS. 6 to 9. A section of expandable tubing 400 is shown beingexpanded from left to right by an expansion tool 402. A foldableelastomeric sleeve 404, which may be identical to sleeve 80 of FIG. 6,is carried on the outer surface of tubing 400. On the right end ofsleeve 404 is a stop ring 406 which may be identical to the ring 82 ofFIG. 6. An outer metal sleeve 408 is carried on tubing 400 adjacent theleft end of the sleeve 404, and has sliding seals 410 between the innersurface of sleeve 408 and the outer surface of tubing 400. An innersliding sleeve 412 is positioned at the location of the outer sleeve 408and connected to it by one or more bolts or pins 414. The pins 414 mayslide axially in corresponding slots 416 through the tubing 400.

In operation of the FIG. 36 embodiment, the leading edge 418 ofexpansion tool 402 is sized to fit within the unexpanded inner diameterof tubing 400 and to push the inner sleeve 412 to the right. As theexpansion tool is driven to the right, it pushes the sleeve 412, whichin turn pushes outer sleeve 408 to the right by means of the pins 414which slide to the right in slots 416. When the pins 414 reach the rightend of the slots 416, the sleeve 404 will have been folded asillustrated in FIG. 6. Further movement of expansion tool 402 shears offthe pins 414 so that the inner sleeve 412 may be pushed on down thetubing 400. As the expansion tool 402 passes through tubing 400, outersleeve 408 and the sleeve 404, all of these parts are further expandedas illustrated in FIG. 7. The inner surface of sleeve 408 preferablycarries a toothed gripping surface 420, like the surface 59 of FIG. 4.When sleeve 408 has moved to the right, gripping surface 420 will beadjacent the outer surface of tubing 400. Upon expansion of the tubing400, it will grip the toothed surface 420 preventing further sliding ofthe outer ring 408. The ring 406 may be adapted to slide in response toexcessive expansion pressures created by undersized boreholes asdiscussed above with reference to FIGS. 3 and 4.

With reference to FIG. 37, there is illustrated yet another system forpreexpanding an externally carried elastomeric sleeve of the type shownin FIGS. 6 to 9. A section of expandable tubing 500 is shown beingexpanded from left to right by an expansion tool 502. A foldableelastomeric sleeve 504, which may be identical to sleeve 80 of FIG. 6,is carried on the outer surface of tubing 500. On the right end ofsleeve 504 is a stop ring 506 which may be identical to the ring 82 ofFIG. 6. On the left end of sleeve 504 is attached a slidable ring 508. Asleeve 510 is slidably carried on the inner surface of tubing 500. Apair of sliding seals 512 provide fluid tight seal between sleeve 510and the inner surface of tubing 500. One or more pins 514 are connectedto and extend radially from the inner sleeve 510. The pins 514 extendthrough corresponding slots 516 in the tubing 500 and are positionedadjacent the left end of the ring 508. The ring 508 preferably carriesgripping teeth 518 on its inner surface.

In operation of the FIG. 37 embodiment, the expansion tool 502 is forcedfrom left to right through the tubing 500. When the tool 502 reaches anedge 520 of the inner sleeve 510, it will begin to push the sleeve 510to the right. The sleeve 510, through pins 514, pushes the outer ring508 to the right compressing and folding sleeve 504 into the shape shownin FIG. 6. When the pin 514 reaches the end of slot 516, the sleeve 510stops moving to the right. The edge 520 of inner sleeve 510 ispreferably sloped to match the shape of expansion tool 502 and limit theamount of force which can be applied axially before the sleeve 510 stopsand is expanded by the tool 502. The tool 502 then passes through sleeve510 expanding it, the tubing 500, the outer ring 508 and the sleeve 504.As this occurs, the teeth 518 grip the outer surface of tubing 500 toresist further slipping of the ring 508. The ring 506 may be adapted toslide in response to excessive expansion pressures created by undersizedboreholes as discussed above with reference to FIGS. 3 and 4.

The embodiments of FIGS. 12 through 16 and 30 (with the inflatablesleeve 330) share several functional features and advantages. These areillustrated in a more generic form in FIGS. 38 through 41. Each of theseembodiments provides a recess or compartment in an expandable tubing inwhich a flowable material used to form an annular isolator is carriedwith the expandable tubing when it is run into a borehole. In eachembodiment it is desirable that sufficient material be carried with thetubing to form an annular isolator in an oversized, washed out andirregular shaped borehole. It is also desirable that the same systemsfunction properly in a nominal or even undersized borehole. In each ofthese embodiments, an expandable outer sleeve has certaincharacteristics which make this multifunction capability possible.

In FIG. 38, a section of expanded tubing 530 is shown in an openborehole 532 having an enlarged or washed out portion 534. An inflatablesleeve 536 is shown having a first portion 538 inflated into contactwith the enlarged borehole portion 534. The sleeve portion 538 isdesigned to allow great expansion at a first pressure level to form anannular isolator in an enlarged borehole wall 534. It may be made ofelastomeric material or expandable metal which is corrugated orperforated or otherwise treated to allow greater expansion. If sleeve536 is corrugated or perforated, it is preferably covered with anelastomeric sleeve. Other portions 540, 542 of the sleeve 536 aredesigned to inflate at pressures higher than the pressure required toinflate the section 538. The volume of fluid carried in the tubing 530as it is run in or installed in the borehole 532 is selected to besufficient to inflate sleeve section 538 to its maximum allowable size.

With reference to FIG. 39, an end view of the enlarged borehole section538, tubing 530 and isolator sleeve section 538 of FIG. 38 is shown. Asillustrated, the borehole section 534 may not only be enlarged, but mayhave an irregular shape, width greater than height and the bottom may befilled with cuttings making it flatter than the top. The flexibility ofsleeve section 538 allows it to conform to such irregular shapes. Thevolume of inflating fluid carried in the tubing 530 should be sufficientto inflate the sleeve 536 into contact with such irregular shaped holesso long as it does not exceed the maximum allowable expansion of thesleeve.

In FIG. 40 is illustrated the same tubing 530 and sleeve 536 is aborehole section 544 which is enlarged, but less enlarged than thewashed out section 534 of FIG. 38. In FIG. 40 the sleeve section 538 hasexpanded into contact with the borehole wall at a smaller diameter thanwas required in FIG. 38. Only part of the fluid volume carried in thetubing 530 was required to expand sleeve section 538. As the tubing 530was expanded after the section 538 contacted the borehole wall, theexpansion fluid pressure increased to a higher level at which the sleevesection 540 expands. The section 540 has also expanded into contact withthe borehole wall 544. In this FIG. 40, the volume of expansion fluidrequired to expand both sections 538 and 540 into contact with theborehole wall is the same as the amount carried down hole with thetubing 530. Complete expansion of the tubing 530 therefore does notcause further inflation of the sleeve 536.

In FIG. 41, the expanded tubing 530 is shown installed in a borehole 546which is not washed out. Instead the borehole 546 is of nominal drilleddiameter or may actually be undersized due to swelling on contact withdrilling fluid. In this case, the outer sleeve section 538 firstexpanded into contact with the borehole at a first pressure level. Theexpansion fluid pressure then increased causing the sleeve section 540to expand into contact with the borehole wall 546. Inflation of thesesections required only part of the volume of fluid carried in the tubing530. As a result, the fluid pressure increased to a third level at whichsleeve section 542 expanded into contact with the borehole 546. In thisillustration, the volume of fluid needed to expand all sections 538, 540and 542 into contact with the borehole wall was less than the totalavailable amount of fluid carried in tubing 530. As a result, the fluidpressure increased to a fourth level at which a pressure relief valvereleased excess fluid into the annulus at 548.

An inflatable sleeve as illustrated in FIGS. 38-41 may have two, threeor more separate sections which expand at different pressures and may ormay not include pressure relief valves. The embodiments of FIGS. 12 and13 have two sleeve sections which expand at different pressures and arelief valve which opens at a third higher pressure. The embodiment ofFIGS. 15 and 16 has three sleeve sections, each of which expands at adifferent pressure level, and as illustrated does not have a pressurerelief valve. The FIGS. 15, 16 embodiment may be provided with apressure relief valve to protect the system from excessive pressure ifdesired. The combinations of these elements provides for maximuminflation to form an annular isolator in a large irregular borehole,while allowing the same system to be inflated to form an annularisolator in a nominal or undersized borehole without causing excessivepressures or forces which may damage the annular isolator formingsleeve, ring, etc., the tubing or an expansion tool.

In FIGS. 2, 10, 33, 34 and 35 there are illustrated conduits located inthe annulus and passing through the annular isolators formed by thoseembodiments. With reference to FIGS. 42, 43 and 44 there are illustratedmore details of embodiments including such conduits. In FIG. 42, asection of expandable tubing 550 has a reduced diameter section 552. Anouter inflatable sleeve 554 extends across the recess 552 to form acompartment for carrying an isolator forming material. An externalconduit 556 passes through the sleeve 554. The conduit 556 may have anopening 557 into the compartment between recess 552 and sleeve 554. FIG.43 provides a more detailed view of a sealing arrangement between thesleeve 554 and the conduit 556 of FIG. 42. A rubber gasket 558 may bepositioned in an opening 560 through each end of the sleeve 554 asillustrated. The conduit 556 may be inserted through the gasket 558. Thegasket forms a fluid tight seal between the conduit 556 and the sleeve554 to prevent flow of fluids between the annulus and the compartmentbetween sleeve 554 and the tubing recess 552.

FIG. 44 illustrates another arrangement for providing one or moreconduits in the annulus where an annular isolator is positioned. Aninflatable sleeve 561 is carried on an expandable tubing 562, forming acompartment in which an annular isolator forming material may be carrieddown hole with the tubing 562. The sleeve 561 has a longitudinal recess564 in which is carried two conduits 566. A rubber gasket 568 hasexternal dimensions matching the recess 564 and two holes for carryingthe two conduits 566. When the sleeve 561 is expanded into contact witha borehole wall to form an annular isolator, the gasket 568 will act asan annular isolator for that portion of the annulus between the conduits566 and the sleeve 561 and will protect the conduits 566.

As discussed above, conduits 556 and 566 may carry various copper orother conductors or fiber optics or may carry hydraulic fluid or othermaterials. In the FIG. 42 embodiment, the side port 557 may be used tocarry fluid for inflating the sleeve 554 if desired. The conduit maypass through a series of sleeves 554 and they may all be inflated to thesame pressure with a single conduit 556 having side ports 557 in eachsleeve. The conduit 556 may be used to deliver one part of a two partchemical system with the other part carried down hole with the tubing.The conduit 556 may be used to couple electrical power to heaters toactivate chemical reactions. Either electrical power or hydraulic fluidmay be used to open and close valves which may control inflation ofannular isolators during installation of a production string, or may beused during production to control flow of produced fluids in each of theisolated producing sections. The dual conduit arrangement of FIG. 44 mayprovide two hydraulic lines which can be used to control and power aplurality of down hole control systems.

With reference to FIG. 45, there is illustrated an elastomeric sleeve580 which may be used as an alternative to sleeve 56 of FIG. 3, sleeves80 and 88 of FIG. 6, or the sleeve 220 of FIG. 21. The sleeve 580 isillustrated in an unrestrained or as-molded shape. Each end 582 is asimple cylindrical elastomeric sleeve. Between the ends 582 are a seriesof circumferential corrugations 584. The corrugations 584 have innercurved portions 586 having an inner diameter corresponding to the innerdiameter of end portions 582. This inner diameter is sized to fit on theouter surface of an unexpanded expandable tubing section. The maximumdiameter of corrugations 584 is sized to contact or come close to thewall of a washed out borehole section without tubing expansion. Ifdesired, wire bands 588 may be used to maintain the corrugated shapewhen the sleeve 580 is compressed as discussed below.

In use, the sleeve 580 is attached to expandable tubing with a slidingring like ring 60 and a fixed ring like ring 58 of FIG. 3. The sleeve580 is then stretched axially until the corrugations are substantiallyflattened against the tubing and the sliding ring is latched into arestraining recess. Note that axial stretching of the elastomer is notessential to flattening the corrugations. The flattened sleeve 580 isthen carried with the tubing as it is installed in a borehole. Uponexpansion of the tubing in the borehole, the sliding ring will bereleased as shown in FIG. 4 and will tend to return to its corrugatedshape. As expansion continues the sliding ring will be pushed by theexpansion cone as shown in FIGS. 6 and 7 to axially compress the sleeve580. The sleeve 580 will take the form shown in FIG. 45 and then befurther compressed until the corrugations 584 are tightly pressedtogether. The wire bands 588 are preferred to maintain the shape afterfull compression. The alternative axial compression and radial expansionsystems shown in FIGS. 36 and 37 may be used with the sleeve 580 ifdesired. It can be seen that by molding the sleeve 580 in the form shownin FIG. 45, the sleeve will have a small radial height as run into theborehole and a very predictable radial height after it has been releasedand returned to its corrugated shape. As with other embodimentsdescribed herein, the sleeve 580 will then be further expanded with theexpandable tubing as the expanding tool passes under the sleeve 580.

As noted above in the descriptions of various embodiments, variousfluids may be used in the present invention to inflate an externalsleeve, bladder, etc. to form an annular isolator or may be injecteddirectly into the annulus between tubing and a borehole wall to form anannular isolator by itself or in combination with external elastomericrings, sleeves, etc. carried on the tubing. These fluids may include avariety of single parts liquids which are viscous or thixotropic ascarried down hole in the tubing. They may include chemical systems whichreact with ambient fluids to become viscous, semisolid or solid. Theymay also include flowable solid materials such a glass beads. In many ofthe above described embodiments an annular isolator is formed of aviscous or semisolid material either directly in contact with a boreholewall or used as a fluid to inflate a metallic and/or elastomeric sleeve.These arrangements not only provide annular isolation in an irregular orenlarged borehole wall, but also allow the isolation to be maintained asthe shape or size of the borehole changes which often occurs during theproduction lifetime of a well.

As is apparent from the above described embodiments, it is desirable toprovide external elastomeric sleeves, rings, etc. which are of minimaldiameter during running in of tubing, but which expand sufficiently toform an annular isolator in irregular and enlarged open borehole. Byproper selection of elastomeric materials, it can swell upon contactwith well bore fluids or setting fluids carried in or injected intoproduction tubing. For example, low acrylic-nitrile swells by as much asfifty percent when contacted by xylene. Simple EPDM compounds swell whencontacted by hydrocarbons. This approach may provide additionalexpansion and isolation in the embodiments shown in FIGS. 2, 4, 5, 6,12, 15, 19, 22, 25, 30, 31, 32, 34 and 35. It may be desirable to encasethe swellable elastomer inside a nonswellable elastomer. Elastomerswhich have been expanded by this method may lose some physical strength.A nonswellable outer layer would also prevent loss of the swelling agentand shrinkage of the swellable material. For example in the embodimentof FIG. 30, the elastomeric sleeve 330 can be made of two layers, withthe inner layer swellable and the outer layer not swellable. The fluid324 can be selected to cause the inner layer to swell. The fluid 324 andinner layer of elastomer would tend to fill the expanded member 330 witha solid or semisolid mass.

It is often desirable for the inflating fluids described herein to be oflow viscosity while being used to inflate a sleeve or being pumpeddirectly into an annulus. Low viscosity fluids allow some of the fluidto flow into microfractures or into the formation to help stop fluidsfrom bypassing the annular isolator. But it is also desirable to havethe injected fluids become very viscous, semisolid or solid once inplace. Many two part chemical systems are available for creating suchviscous, semisolid, rubbery or solid materials. Some, for example thesilicone materials or the polyacrylamide materials, react with availablewater to form a thick fluid. Others require a two part chemical systemor a catalyst to cause the chemicals to react. The FIG. 10 embodimentdelivers two chemical components in dry condition to be reacted togetherwith ambient water. The FIG. 24 embodiment delivers and mixes a two partchemical system to the location where an annular isolator is needed. Inthe embodiment of FIGS. 13 and 14, the corrugated tubing section 160provides four separate compartments in which various chemical systemsmay be carried with the tubing as installed to be mixed upon expansionof the tubing. In other embodiments, such as those shown in FIGS. 12through 16, the delivery system includes a single recess or compartment.In these embodiments, a two part chemical system can be used byencapsulating one part of the chemical system, or a catalyst, in bags,tubes, microspheres, microcapsules, etc. carried in the other part ofthe chemical system. By selecting the sizes and shapes of suchcontainers, they will rupture during the expansion process allowing thematerials to mix and react. For example, in the FIG. 30 embodiment, theport 326 can be shaped to cause rupturing of such bags, tubes,microcapsules, etc. and mixing of the materials as they pass through theport.

As noted above, any one of the annular isolators 28, 30, 36, 38 shown inFIG. 1, may actually comprise two or more of the individual isolatorsillustrated in other figures. If desired, pairs of such individualisolators may be arranged closely to provide separate recesses orstorage compartments for carrying each part of a two part chemicalsystem in the tubing, to be mixed only after tubing expansion. Forexample, an embodiment according to FIG. 12 or 13 could be spaced ashort distance up hole from an embodiment like FIG. 11. The FIG. 11embodiment could carry a catalyst for the material carried in the FIG.12 or 13 embodiment. Excess fluid vented through the pressure reliefmechanism of the FIG. 12 or 13 embodiment would be vented down holetoward the FIG. 11 embodiment, which upon expansion would release thecatalyst into the borehole causing the vented fluid to become viscous,semisolid or solid. In similar fashion, the FIG. 30 embodiment couldinclude two internal sleeves 322 each carrying one part of a two partchemical system and each having a port 326 located between the pair ofelastomeric rings 328. Upon expansion, both parts of the chemical systemwould be injected into the annulus and isolated between rings 328 to mixand react. Alternatively, any one of the described individual isolatorsmay include one of the one-component chemicals or swellables to beejected from the relief system and form an annular isolator on contactor reaction with the ambient fluids in the annulus. Under either ofthese approaches, both a mechanical isolator or isolators (e.g. theinflatable member(s)) and a chemical or swellable isolator (formed as aresult of the materials ejected through the relief systems into theannulus) are formed in proximity to each other in the same annulus.

In the embodiments illustrated in FIGS. 11-16, 24, 25, 30, and 38-41, anannular isolator forming material is preferably carried down hole in areservoir or compartment formed in part by a tubing wall. In FIGS. 11-16the inflation fluid compartment is formed between a reduced diameterportion of the tubing and an outer sleeve. In FIG. 30, a compartment isformed between an inner sleeve and the inside surface of a tubing. Ineither case, the material is carried down hole with the tubing as it isrun in or installed in the borehole. It is preferred that thecompartment be entirely, or at least in part, located within the outerdiameter of the tubing as it is run in the borehole. This allows asufficient volume of material to inflate a sleeve or bladder, or to forman annular isolator in the annulus, to be carried down hole, but doesnot require, or minimizes, reduction in the tubing diameter to providean overall system diameter small enough to be installed in the borehole.It is desirable for the tubing to have the largest possible diameter asinstalled, so that upon expansion it can reduce the annulus size as muchas possible.

Many of the above-described embodiments include the use of an expansioncone type of device for expansion of the tubing. However, one of skillin the art will recognize that many of the same advantages may be gainedby using other types of expansion tools such as fluid powered expandablebladders or packers. It may also be desirable to use an expandablebladder in addition to a cone type expansion tool. For example, if agood annular isolator is not achieved after expansion with a cone typetool, an expandable bladder may be used to further expand the isolatorto achieve sealing contact with a borehole wall. An expandable bladdermay also be used for pressure or leak testing an installed tubingstring. For example, an expandable bladder may be expanded inside thetubing at the location where an annular isolator has been installedaccording to one of the embodiments disclosed herein. The tubing may bepressured up to block flow in the tubing itself to allow detection ofannular flow past the installed isolator. If excessive leakage isdetected, the bladder pressure may be increased to further expand theisolator to better seal against the borehole wall.

In many of the above described embodiments the system is illustratedusing an expansion tool which travels down hole as it expands expandabletubing and deploys an annular isolator. Each of these systems mayoperate equally well with an expansion tool which travels up hole duringthe tubing expansion process. In some embodiments, the locations ofvarious ports and relief valves may be changed if the direction oftravel of the expansion tool is changed. For horizontal boreholes, theterm up hole means in the direction of the surface location of a well.

Similarly, while many of the specific preferred embodiments herein havebeen described with reference to use in open boreholes, similaradvantages may be obtained by using the methods and structures describedherein to form annular isolators between tubing and casing in casedboreholes. Many of the same methods and approaches may also be used toadvantage with production tubing which is not expanded afterinstallation in a borehole, especially in cased wells.

While the present invention has been illustrated and described withreference to particular apparatus and methods of use, it is apparentthat various changes can be made thereto within the scope of the presentinvention as defined by the appended claims.

1. A system for forming an annular isolator between expandable tubingand a borehole comprising: a section of expandable tubing, a compartmentformed in said expandable tubing, an annular isolator forming materialcarried in said compartment, an inflatable member carried on the outersurface of said expandable tubing, and a flow path from said compartmentto said inflatable member said inflatable member comprises a bladder,further including a piston adapted for driving said annular isolatorforming material from said compartment through said flow path into saidbladder, a compressed spring coupled to said piston, and a springrestraining means adapted to release said spring upon expansion of saidtubing.
 2. A system according to claim 2, wherein said restraining meanscomprises a weld adapted to break upon expansion of said tubing.
 3. Asystem for forming an annular isolator between tubing and a borehole,comprising: a section of expandable tubing, two annular rings ofelastomeric material carried on the outer surface of said tubing,whereby, when said tubing is installed in a borehole and expanded, saidrings at least partially block flow of fluids in an annulus between saidtubing and the borehole wall, means for placing an annular isolatorforming material between said pair of annular rings, a band ofchemically reactive materials carried on said tubing between said pairof annular rings.
 4. A system according to claim 3, wherein saidmaterials are incased in a protective covering preventing chemicalreactions from occurring when said tubing is unexpanded and allowingchemical reactions to occur when said tubing is expanded.
 5. A systemaccording to claim 4, wherein said materials are two components of anacid base cement which react in the presence of water.
 6. A systemaccording to claim 5, wherein said materials are magnesium oxide andmonopotassium phosphate.
 7. A system for forming an annular isolatorbetween tubing and a borehole, comprising: a section of expandabletubing, two annular rings of elastomeric material carried on the outersurface of said tubing, whereby, when said tubing is installed in aborehole and expanded, said rings at least partially block flow offluids in an annulus between said tubing and the borehole wall, a portfrom an inner wall of said tubing to an outer wall of said tubingbetween said two annular rings, a work string in said tubing having aflow path from the surface location of said borehole to the port.
 8. Asystem according to claim 7, further comprising an expansion toolcarried on said work string.
 9. A system for forming an annular isolatorbetween tubing and a borehole comprising: a section of tubing, anelastomeric sleeve carried on the outer wall of said tubing, said sleevehaving a generally cylindrical shape when free of external forces and,in response to axial compression, folding along circumferential lines totake a circumferentially corrugated shape, and means for compressingsaid sleeve axially in a borehole.
 10. A system according to claim 9,further comprising a plurality of rings of reduced thickness in saidsleeve, said rings axially spaced along said sleeve and defining foldpoints.
 11. A system for forming an annular isolator between tubing anda borehole comprising: a section of expandable tubing, an elastomericsleeve carried on the outer wall of said tubing, said sleeve having agenerally cylindrical shape having a first axial dimension and a firstradial dimension when free of external forces and, in response to axialcompressive force, having a second axial dimension shorter than saidfirst axial dimension and a second radial dimension greater than saidfirst radial dimension, means for applying axial compressive force tosaid sleeve in a borehole, wherein said sleeve has a first end and asecond end, a first ring coupled to said sleeve first end and coupled tosaid tubing, a second ring coupled to said sleeve second end andslidably coupled to said tubing, said second ring shaped to slideaxially along said tubing and apply compressive force to said sleeve inresponse to expansion of said tubing by a cone type expansion tool, aninternal sleeve slidably carried within said tubing and coupled to saidsecond ring, said internal sleeve shaped to engage and move with a conetype expansion tool moving through said tubing and to move said secondring axially on said tubing.
 12. A system for forming an annularisolator between tubing and a borehole comprising: a section ofexpandable tubing, an elastomeric sleeve carried on the outer wall ofsaid tubing, said sleeve having a generally cylindrical shape having afirst axial dimension and a first radial dimension when free of externalforces and, in response to axial compressive force, having a secondaxial dimension shorter than said first axial dimension and a secondradial dimension greater than said first radial dimension, and means forapplying axial compressive force to said sleeve in a borehole, wherein:said tubing comprises two sections coupled by a threaded connection,said elastomeric sleeve is carried between said two sections, wherebyupon making up of the threaded connection an axial compressive force isapplied to said elestomeric sleeve.
 13. A system according to claim 12,further including: a work string adapted to rotatably engage one of saidtwo sections, whereby upon rotation of said work string, axialcompressive force may be applied to said elastomeric sleeve.
 14. Asystem for forming an annular isolator between tubing and a boreholecomprising: a section of expandable tubing, an elastomeric sleevecarried on the outer wall of said tubing, said sleeve having a generallycylindrical shape having a first axial dimension and a first radialdimension when free of external forces and, in response to axialcompressive force, having a second axial dimension shorter than saidfirst axial dimension and a second radial dimension greater than saidfirst radial dimension, means for applying axial compressive force tosaid sleeve in a borehole, a cylinder divided into first and secondchambers by a seal adapted to break upon expansion of said tubing, afirst part of two part hypergolic chemical system in said first chamber,a second part of two part hypergolic chemical system in said secondchamber, and a piston in said cylinder coupled to said sleeve, wherebyupon expansion of said tubing and breaking of said seal, a hypergolicreaction drives said piston to compress said seal.
 15. A system forforming an annular isolator between tubing and a borehole comprising: asection of tubing in a borehole, a conduit in the annulus between saidtubing and said borehole, and an annular isolator filling the spacebetween said tubing, said conduit and said borehole.
 16. A method forforming an annular isolator between tubing and a borehole comprising:installing an elastomeric sleeve on an expandable tubing section,installing the tubing section in a borehole, increasing the radialdimension of said sleeve, and expanding said tubing.
 17. A methodaccording to claim 16, wherein: said sleeve has a first radial dimensionwhen free of external forces, said step of installing said sleeve onsaid expandable tubing section comprises applying an axial stretchingforce to said sleeve to reduce its radial dimension to a second radialdimension smaller than said first radial dimension, and said step ofincreasing the radial dimension of said sleeve comprises releasing saidaxial stretching force.
 18. A method according to claim 17, wherein saidaxial stretching force is released by expansion of said tubing.
 19. Amethod according to claim 16, wherein said step of increasing saidradial dimension comprises applying an axial compressive force to saidsleeve.
 20. A method according to claim 19, wherein said axialcompressive force is applied to said sleeve by expansion of said tubing.21. A method according to claim 20, further comprising installing a ringon said tubing adjacent one end of said elastomeric sleeve, said ringadapted to slide on said tubing in response to movement of a cone typeexpansion tool through said tubing and to apply axial compressive forceto said sleeve.
 22. A method according to claim 16, wherein: said sleevehas a first radial dimension when free of external forces, said step ofinstalling said sleeve on said expandable tubing section comprisesapplying an radial compressive force to said sleeve to reduce its radialdimension to a second radial dimension smaller than said first radialdimension, and said step of increasing the radial dimension of saidsleeve comprises releasing said radial compressive force.
 23. A methodaccording to claim 22, wherein said radial compressive force is releasedby expanding said tubing.
 24. A method for forming an annular isolatorbetween expandable tubing and a borehole comprising: attaching anelastomeric sleeve to a section of expandable tubing, installing thetubing in a borehole, expanding the tubing with a first expansion toolhaving a fixed expansion diameter, and further expanding the tubing inthe location of said sleeve.
 25. The method according to claim 24,further comprising using a variable expansion cone to further expand thetubing in the location of said sleeve.
 26. The method according to claim24, further comprising applying pressure inside the tubing in thelocation of said sleeve to further expand said tubing.
 27. The methodaccording to claim 26, further comprising applying axial compression tosaid tubing in the location of said sleeve.
 28. The method according toclaim 24, further comprising using an expandable bladder at the locationof said sleeve to further expand said tubing.
 29. The method accordingto claim 24, further comprising swelling the elastomeric sleeve in theborehole.
 30. The method according to claim 29, further comprisingswelling the elastomeric sleeve by exposing the elastomeric sleeve tofluid in the borehole.